A few days ago I had my Nokia Lumia 920 on charge, I restarted the phone and I saw the battery 'empty icon'. It was considering before the restart the phone had 100% charge. When I unplugged the device, it would show the low battery screen. I fixed it by soft reset and it fixed it but again today I had to soft reset it. Does anyone else have this problem? What causes it? Should I hard reset my phone? If it helps I have my phone on charge when at home.